Steering wheel pulsing while braking

Hello all!! Quick question:

 

I just got my Legacy GT this past Monday night. I have noticed that when I am driving at highway speeds (generally anything over 55mph) and I brake; nothing too hard; I can feel a pulsing in the steering wheel. It seems like more on the left hand side of the steering wheel? Any thoughts of what is wrong? I do plan on having Subaru look at it on my first service visit but I would like to hear what suggestions people have.

I wouldn't wait till your first service apt, I would just go take it in now. It should be covered under warranty.

^

 

+1

 

-a

Could be a warped rotor. Legacy05 is right though, don't wait, take it in ASAP.

Could be a warped rotor. Legacy05 is right though, don't wait, take it in ASAP.

 

almost certainly a warped rotor. Bet it got washed right after driving it. This is a no no...spraying cool water on a hot rotor. It's also why I avoid puddles on dry days!!

almost certainly a warped rotor. Bet it got washed right after driving it. This is a no no...spraying cool water on a hot rotor. It's also why I avoid puddles on dry days!!

 

Thats a myth. Rotors don't warp, they get uneven deposits if the rotors are really hot and pad material transfers semi-permenantly onto your rotors in chunks.

 

http://www.stoptech.com/whitepapers/warped_rotors_myth.htm

 

For the original poster, just take it in. They'll resurface or replace your rotors and pads under warranty (hopefully).

Good information in that link. I stand corrected, and come out of this a much enlightened person. Thanks!

Actually I had a bad case of teh warpage, and since then I've changed my braking style to:

 

1. 1-2 light and long pulses

2. Start a gradual increase in pedal pressure and hold midway

3. Then increase pedal pressure to full range

 

This stopped the pulsation I get. Either my new braking technique has removed the uneven deposits, evened out the deposits or the pads/rotors have to heat up a lil and then they mate perfectly. Just another option you can try before going to the dealer.

eh, I fixed my warped rotors with some crazy hard braking from 110+ mph down to 30 mph (at the track and you can hear it in my videos of me at the track, see "motorsports" forums for the thread).. I know what you experiencing of that heavy pulses you get from high speed braking. I doubt it's warped rotors, more like just brake pad deposits. I just only get them when I have driven the car and just rode on the brakes a bit and leaving some large imprints. It's very possible that the stock rotors are considered "soft" to begin with. It's very possible that the calipers have a lot of clamping force.. it's also possible that because it's a 2-piston caliper and possibly a poor master cylinder design, the caliper is squeezing the pads unevenly as well as squeezing the brakes non-symetrically (left first, then right), causing the wheel to shake back and forth or experiencing wheel-pull when you hit the brakes).

 

Still get your car checked out now while you are at it.

 

Keefe

Actually I had a bad case of teh warpage, and since then I've changed my braking style to:

 

1. 1-2 light and long pulses

2. Start a gradual increase in pedal pressure and hold midway

3. Then increase pedal pressure to full range

 

This stopped the pulsation I get. Either my new braking technique has removed the uneven deposits, evened out the deposits or the pads/rotors have to heat up a lil and then they mate perfectly. Just another option you can try before going to the dealer.

 

what you describing is what racers do to the brakes called pad-knockback.. it's usually done on the straights with a few light taps on the brakes that doesnt slow the car down, but to get the pads to not tough the rotors when the brakes are not on.

 

Keefe

what you describing is what racers do to the brakes called pad-knockback.. it's usually done on the straights with a few light taps on the brakes that doesnt slow the car down, but to get the pads to not tough the rotors when the brakes are not on.

 

Keefe

 

You're refering to step 1 only, right ?

yea, it's that tap of the brakes (usually LFB) to get the pads to not stick and scrape on the rotor when the brakes are relaxed.

 

Keefe

On my '02 WRX I had a pulsating pedal just as the car was coming to a stop. Dealer checked it and he said it was warped rotors. I had 35,000 miles on car. They replaced front rotors under warranty. He said the pads weren't worn enough under company guidelines to replace them also. Apparently rotors are covered on the 36,000 mile bumper to bumper..

 

Didn't know pads were, though. Maybe I would have had to pay for the pads if they were worn down.

On my '02 WRX I had a pulsating pedal just as the car was coming to a stop. Dealer checked it and he said it was warped rotors. I had 35,000 miles on car. They replaced front rotors under warranty. He said the pads weren't worn enough under company guidelines to replace them also. Apparently rotors are covered on the 36,000 mile bumper to bumper..

 

Didn't know pads were, though. Maybe I would have had to pay for the pads if they were worn down.

 

I assume that fixed the pulsating pedal, but did it resurface later on ?

All fixed and never reoccurred, even under hardest braking.

All fixed and never reoccurred, even under hardest braking.

 

Thanks, will get my rotors turned on my next oil change.

Remeber guys...this is pulsating in the steering wheel...not the brake pedal. I set up an appointment with the dealership to look at this Thursday. I will keep you posted.

 

Rob

Remeber guys...this is pulsating in the steering wheel...not the brake pedal. I set up an appointment with the dealership to look at this Thursday. I will keep you posted.

 

Rob

 

Didn't you say it pulsates ONLY under braking? If the steering wheel pulsates it can be a wheel balance weight fell off, a front tire(s) is flat spotted, or certain grooved road surfaces cause it. Is it effected by speed? (wheel imbalance pulsating comes and goes at certain speeds).

 

Nothing in the steering column could create pulsating. It all feeds back from the FRONT END rotating masses (rotors, tires, CV joints). Tires out of round are a pain. Best way is to rotate the fronts to the rear and see if it goes away. Some tire dealers can shave an out-of-round tire on a tire lathe but it's getting hard to find those dealers. Maybe truck tire outfits.

 

By the way, nobody has mentioned the possibility of rotors warping when an impact gun is used to tighten wheel lugs in the wrong sequence (pattern) and overly tight.

 

They (your dealer) should be able to isolate it. Suggest that they temporarily slip on a new set of front rotors and then road test it. Simple 15 minute experiment. Or they will micrometer check the runout on the rotors. Good luck.

Yes...I am sorry...I should have elaborated.

 

 

The problem only happens when I am braking and I feel it only in the steering wheel. I will keep you guys posted after the dealer visit.

There 2 possibilites:

 

1. Wheels are out of balance, so even if the vibration is minimal and not very noticable, applying the brakes pushes the pads against the rotor that is rotating much faster and therefore the vibration is magnified and more noticable

 

2. Uneven pad deposits on (aka warped) rotors, this feels like the car is applying inconsistent brake pressure. At low speeds, you can feel the brakes grabbing, then freeing up/car lurches, brakes grab again, rinse and repeat. The pads are not maintaining constant contact to the rotors, because the uneven deposits throws them off.

 

The difference between both, is that the first possibility(wheel out of balance) would only happen at highway speed, (50 and above), and is sometimes identifiable by slight steering wheel vibration without braking, while the warped rotors cause steering wheel vibration when braking at highway speeds and inconsistent braking at slow speeds.

Mine's going to the dealer Friday. Steering wheel shimmy with braking. Worse when brakes hot. At the bottom of a big hill, you can actuall see the steering wheel shimmy, and now I'm starting to hear a pulsating noise from the front when all of this is going on.

 

Miles? About 1,300. Problem getting increasingly worse, hence, need for unscheduled maintenance visit.

 

I know the dealer will treat me right, I just hope they are able to diagnose and fix the problem the first time.

 

It takes the fun out of going fast when you know the slowing down is going to suck.

I am feeling the same problem on my 450 mile brand new LGT 5eat. Guess it is a warped rotor and I will need to take it back to get fixed I hate that

Before taking it back, have you tried some high g braking exercizes to attempt to clean off the rotor? It has worked for me in the past. Just take it to about 60 mph, ensure no one is behind you, and then put the brakes to the floor, engaging the ABS. Do this once or twice and then drive for a bit to cool the pads and rotors off, then see if it still pulses.

I have the same thing at 10,500 miles. Actually, I get some slight steering wheel shimmy on normal driving and worse on braking. Just changed tires and thinking rotors and/or tire imbalance. Going in soon...